The present invention relates to a preset lighting device in which input and output terminals are adapted to be switchable.
Generally, preset lighting devices of this type have been provided with separate input and output terminals. Such preset lighting devices are, however, disadvantageous in that a great amount of space is needed for the attachment of the terminals, especially in the case the device is provided as an integrated circuit.
Microcomputer ICs often have input and output terminals common to each other for which input and output operations are performed on a time-shared basis by the application of appropriate clock pulses. With this arrangement, following an output operation, some waiting time is required before input signals can be received and inputs of short duration may not be recognized.
An object of the invention is thus to reduce the number of the circuits using common input and output terminals. A further object of the invention is to provide a circuit which does not respond to a duplicate push so that an instantaneous state is held and to provide a circuit in which a lighting condition presently held is extinguished after which a new lighting condition is maintained. A still further object is to provide a circuit capable of input and output operations in real time.